Naslov
Ultrasound extracted flavonoids from four varieties of Portuguese red grape skins determined by reverse-phase high-performance liquid chromatography with electrochemical detection

Autori
Novak, Ivana ; Janeiro, Patricia ; Šeruga, Marijan ; Oliveira-Brett, Ana Maria

Izvornik
Analytica Chimica Acta (0003-2670) 630 (2008), 2; 107-115

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
reverse-phase high-performance liquid chromatography (RP-HPLC); electrochemical detection; flavonoids; antioxidants; red grape skins; ultrasound extraction

Sažetak
Several flavonoids present in red grape skins from four varieties of Portuguese grapes were determined by reverse-phase high-performance liquid chromatography (RP-HPLC) with electrochemical detection (ECD). Extraction of flavonoids from red grape skins was performed by ultrasonication, and hydrochloric acid in methanol was used as extraction solvent. The developed RP-HPLC method used combined isocratic and gradient elution with amperometric detection with a glassy carbon working electrode. Good peak resolution was obtained following direct injection of a sample of red grape extract in a pH 2.20 mobile phase. Eleven different flavonoids: cyanidin-3-O-glucoside (kuromanin), delphinidin-3-O-glucoside (myrtillin), petunidin-3-O-glucoside, peonidin-3-O-glucoside, malvidin-3-O-glucoside (oenin), (+)-catechin, rutin, fisetin, myricetin, morin and quercetin, can be separated in a single run by direct injection of sample solution. The limit of detection obtained for these compounds by ECD was 20-90 pg/L, 1000 times lower when compared with photodiode array (PDA) limit of detection of 12-55 ng/L. RP-HPLC-ECD was characterized by an excellent sensitivity and selectivity, and appropriate for the simultaneous determination of these electroactive phenolic compounds present in red grape skins.

Izvorni jezik
Engleski

Znanstvena područja
Prehrambena tehnologija

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